In the 3rd generation partnership project (3GPP), evolution of a radio access system and a radio network for the cellular mobile communication (hereinafter, referred to as “Long Term Evolution (LTE)” or “Evolved Universal Terrestrial Radio Access (EUTRA)”) and the radio access system and the radio network that realize higher-speed data communication utilizing frequencies in a wider band, (hereinafter, referred to as “Long Term Evolution-Advanced (LTE-A)” or “Advanced Evolved Universal Terrestrial Radio Access (A-EUTRA)”) are considered.
In LTE, orthogonal frequency division multiplexing (OFDM) system that is a multi-carrier transmission is used as a downlink, and a single-carrier communication system of SC-FDMA (Single-Carrier Frequency-Division Multiple Access) system that is a single-carrier transmission is used as an uplink. In LTE, such channels are allocated to the radio communication from a base station apparatus to a mobile station apparatus (the downlink) as a physical broadcast channel (PBCH), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical multicast channel (PMCH), a physical control format indicator channel (PCFICH), and a physical HARQ (hybrid automatic repeat request) indicator channel (PHICH).
A physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH) are allocated to the radio communication from the mobile station apparatus to the base station apparatus (the uplink).
In LTE, to control interferences among base stations, to save electric power of the mobile station apparatus, etc., the transmission power of the physical uplink control channel, the physical uplink shared channel, and a sounding reference signal that is transmitted by the mobile station apparatus to measure the quality of the uplink channels is controlled using a plurality of parameters. The parameters for controlling the transmission power include a parameter based on a path loss measured by the mobile station apparatus from a downlink signal and parameters notified of by the base station apparatus to the mobile station apparatus. The parameters notified of by the base station apparatus to the mobile station apparatus include a parameter commonly set among mobile station apparatuses and a parameter set in each of the mobile station apparatus. A “TPC command (Transmission Power Control command)” is transmitted in the physical downlink control channel, that is a parameter for each of the mobile station apparatuses and that is notified of by the base station apparatus to the mobile station apparatus (see Chapter V of Non-Patent Literature 1).
Section 5.3.3 of Non-Patent Literature 2 describes a format of downlink control information that is transmitted in the physical downlink control channel. A format indicating the allocation of radio resources of the physical uplink shared channel includes a TPC command for the physical uplink shared channel and the sounding reference signal. Hereinafter, this format will be referred to as “uplink grant”. A format indicating the allocation of radio resources of the physical downlink shared channel includes a TPC command for the physical uplink control channel. Hereinafter, this format will be referred to as “downlink grant” or “downlink assignment”.
A “format 3” and a “format 3A” are defined, that include only a plurality of TPC commands for a plurality of mobile station apparatuses. For the format 3 and the format 3A, the number of bits of the TPC commands included in each format differs from that of each other. Hereinafter, the format 3 and the format 3A will be collectively referred to as “format 3/3A”. The base station apparatus notifies the mobile station apparatus of an identifier and one number. The mobile station apparatus recognizes a TPC command of the number notified of from the base station apparatus that is included in the format 3/3A that includes the identifier notified of from the base station apparatus as a TPC command addressed to the mobile station apparatus. To identify whether the TPC command included in the format 3/3A is for the physical uplink control channel or for the physical uplink shared channel and the sounding reference signal, the base station apparatus allocates two identifiers and allocates one number to each of these identifiers. The identifier corresponding to the physical uplink control channel is referred to as “TPC-PUCCH-RNTI (Transmission Power Control-Physical Uplink Control Channel-Radio Network Temporary Identifier)” and the identifier corresponding to the physical uplink shared channel and the sounding reference signal is referred to as “TPC-PUSCH-RNTI (Transmission Power Control-Physical Shared Control Channel-Radio Network Temporary Identifier)”.
A plurality of mobile station apparatuses need to receive the format 3/3A and, therefore, the format 3/3A is located in a common search space for all of the mobile station apparatuses to search the physical downlink control channel and are not located in a user equipment-specific search space that has a physical downlink control channel addressed to a specific mobile station apparatus disposed therein. The format 3/3A is used for the base station apparatus to transmit the TPC command to control the transmission power of a signal in the uplink of the mobile station apparatus, when, for example, the base station apparatus allocates no radio resources to the mobile station apparatus in the physical uplink shared channel using the uplink grant and in the physical downlink shared channel using the downlink grant and the mobile station apparatus regularly transmits the physical uplink shared channel, and the sounding reference signal and physical uplink control channel for the physical downlink shared channel.
It is required to LTE-A that LTE-A has the compatibility with LTE, that is, that a base station apparatus based on LTE-A is enabled to simultaneously execute radio communication with both of a mobile station apparatus based on LTE-A and that based on LTE, and a mobile station apparatus based on LTE-A is enabled to execute radio communication with both of a base station apparatus based on LTE-A and that based on LTE. Therefore, using the same channel structure as that of LTE is considered for LTE-A.
For example, a technique is proposed for LTE-A of using a plurality of frequency bands each having the same channel structure as that of LTE (hereinafter, referred to as “carrier component (CC)” or “component carrier (CC)”) as one frequency band (a wideband frequency band) (“frequency band aggregation”, also referred to as “spectrum aggregation”, “carrier aggregation”, “frequency aggregation”, etc.).
More specifically, in communication using the frequency band aggregation, the physical broadcast channel, the physical downlink control channel, the physical downlink shared channel, the physical multicast channel, the physical control format indicator channel, and the HARQ indicator channel are transmitted for each downlink carrier component, and the physical uplink shared channel, the physical uplink control channel, and the physical random access channel are allocated to each uplink carrier component. The frequency band aggregation is a technique that a base station apparatus and a plurality of mobile station apparatuses simultaneously transmit and receive pieces of data and pieces of control information using a plurality of carrier components such as the physical uplink control channel, the physical uplink shared channel, the physical downlink control channel, and the physical downlink shared channel in the uplink and the downlink (see Chapter V of Non-Patent Literature 3).